To install large, fixed phased-array antennas such as those used on naval vessels, the flatness of the foundation to which the arrays are mounted is one important factor. If the profile of the antenna array mounting flange does not match the foundation, system performance may be adversely affected. Accordingly, the foundation profile must be precisely measured at the antenna array mounting holes so that shims of proper thickness may be fabricated to achieve a proper fitment. The mounting flanges of some large antenna arrays may typically be on the order of approximately 12-14 feet across and have bolting patterns of comparable size. Foundations for these arrays typically are oriented at about 15° tilted back from vertical and comprised of heavy steel plate having a large central opening and a plurality of mounting holes for receiving bolts for mounting the array.
To take the foundation profile measurements, an optical alignment telescope is used which heretofore has been held in a fixture temporarily mounted near the center of foundation opening. This location is not generally accessible from a permanent regular access deck or walkway, and usually is approximately 10-12 feet up in the air. This requires a temporary scaffold to be erected inside the antenna array equipment room for access. Before shim measurements may be taken, however, the telescope fixture must be precisely aligned or “bucked in” with the foundation so that accurate flatness measurements can be obtained parallel to the plane or face of the foundation. Conventional fixture alignment methods have relied on complex and time-consuming optical-based procedures requiring a minimum of two technicians. One technician works the alignment telescope from the scaffold inside the antenna array equipment room while another technician is positioned on a scaffold outside the equipment room. The outside technician is equipped with a ruler or scale which alternatingly is held at a minimum of three different locations around the central foundation opening while the inside technician observes the measurements at each location. The fixture is then adjusted and measurements are repeated multiple times until the fixture is finally optically aligned with the foundation. This procedure typically takes an hour or more to buck in the fixture before shim flatness measurement can be started and is an arduous task.
Accordingly, an improved method of aligning or bucking in an alignment telescope fixture with an antenna array foundation is desired.